Just got done with a new item that might be useful
http://www.joedios.com/dioramas/sho...php?i=23907&c=8
I recommend saving two version: one at the default 480 x 600 dimensions an the other at original 575 x 719 dimensions. That way you can make a small and a larger versions of the sand barriers.
Just got ink so I'll post pics with Joes soon.